1) Revocation refers to the cancellation of a granted patent by requesting that the patent be revoked. Opposition refers to opposing the grant of a patent before or after it is granted.
2) Pre-grant opposition must be filed before a patent is granted, whereas post-grant opposition must be filed within one year of the patent being granted. Revocation can be requested at any time during the life of a patent.
3) In addition to opposing a patent grant, any interested person can file to revoke a granted patent under Section 64 of the Indian Patent Act of 1970.